Is it normal that I’m losing appetite with regular exercise?

I would assume that if you use more energy you would need more food. However, I find that after exercise I’m usually not hungry for a number of hours. While my exercise has been going very well I am wondering if my lack of hunger will hinder my growth of muscle mass(which has been rapid and successful, so far). I’m only 17 years old so I imagine I don’t have any serious health concerns that would cause it.

Why am I less hungry?

You probably just don’t "feel" hungry. This is pretty normal. One of the things that athletes have trouble with is packing in the calories for this very reason. You just have to force yourself to eat and eat the right things (high protein etc). Had a trainer put me on 2 lbs of meat a day in addition to other things. Gives you gas, but helps get the protein. Also limit the amount of unnatural sugar that you get. This should help some. Drink water all the time.

Oh yeah, and some of the reason you don’t feel hungry is due to the release of hormones (feel good things) that take the hunger feeling away….but you will find that it is pretty normal. Just eat even though you don’t feel like it.